Corrugated tube coupling means

ABSTRACT

A thermoplastic coupling for corrugated plastic tubing having an elongated generally cylindrical body and mouth at either end. The inside diameter of the cylindrical body approximates the outside major diameter of the corrugated tubing. Cleats along the inner circumference of the mouth have inwardly directed vertical faces and inwardly converging camming surfaces in order to permit the tubing to enter the coupling but impede its removal. Optionally the coupling may have a corrugated body. Where the coupling feature of this invention is employed in connection with a fitting such as a Tee it is preferred that the body be corrugated. A Tee coupling may be formed by including a branch which protrudes outwardly from the side of and in fluid communication with the cylindrical coupling body.

United States Patent 1151 3,695,643 Schmunk [45] Oct. 3, 1972 CORRUGATEDTUBE COUPLING FOREIGN PATENTS OR APPLICATIONS MEANS 6,802,270 8/ 1968Netherlands ..285/226 [72] Inventor: John D. Schmunk, Findlay, OhioPrimary Examiner-D. J Williamowsky [73] Assignee The Hancock q & TueCam- Assistant Examiner-David H. Corbin pally Fmdlay Ohm Attorney-ThomasD. Shaffner [22] Filed: May 18, 1970 [21] App]. No.: 38,437 [57]ABSTRACT A thermoplastic coupling for corrugated plastic tubing havingan elongated generally cylindrical body and [52] US. Cl. ..285/156,285/235, 285/417, mouth at either end The inside diameter f the cy]in285/423, 285/D1G. 4 drical body approximates the outside major diameter[51] Int. Cl. ..F16] 21/00, F161 41/00 of the corrugated tubing, Cleatsalong the inner cir-' [58] Field of Search ..285/7, 226, 235, 260, 304,cumference of the mouth have inwardly directed verti- 285/305, 317, 417,424, DIG. 4, DIG. 21, cal faces and inwardly converging camming surfaces156; 138/121, 122; 61/16 in order to permit the tubing to enter thecoupling but impede its removal. Optionally the coupling may have [56]References Cit d a corrugated body. Where the coupling feature of thisinvention is employed in connection with a fitting such UNITED STATESPATENTS as a Tee it is preferred that the body he corrugated. A1,324,602 12/1919 Lorenz ..285/305 X cmpling may be famed by incluqing aWhlCh protrudes outwardly from the side of and in 2,524,629 10/ 1950Liedtke ..285/226 X fluid communication with the cylindrical coupling3,212,799 10/1965 Rice ..285/235 body 3,239,254 3/1966 Campbell..285/424 X 3,317,087 5/1967 Landis ..285/235 X 8 Claims, 6 DrawingFigures PATENTED 3 I972 sum 1 or 2 INVENTOR. JOHN D. SCHMUNK BY p 38 3 4M 4h ATTORNEYS CORRUGATED TUBE COUPLING MEANS BACKGROUND OF THEINVENTION When drainage systems comprised of sections of corrugatedplastic tubing are laid it is necessary to connect adjoining sections bycouplings. The ideal coupling should be inexpensive, assemble easily,hold securely, and not require any special modifications of the tubeends. Simplicity of assembly is particularly important. Any complicatedor critical connections with the tubing requires unnecessary labor andmay result in a faulty connection which will separate when covered withsoil. Soil may then enter the line and block it.

Simplicity of assembly also reduces the time necessary to lay thedrainage tile and therefore its effective cost. If a number ofmanipulations are necessary to physically connect a coupling and adrainage line it naturally takes longer than one similar action. Forexample, if it is necessary to put some type of seal between the partsand then connect them it will take longer than simply connecting them.Ideally, the parts should be connected by simply inserting one into theother.

It is also highly preferable if different lengths of tubing can beinserted into the mouth of the coupling while maintaining a secureconnection. If a specific length of the tubing has to be inserted intothe mouth of the coupling it will he often necessary in connection witha system which is made up, to cut the tubing or rearrange the entiresystem in order to attain the specific insertion length required. Theadditional time and labor required to fit the tubing naturally adds tothe cost and would undoubtedly result in some failures.

Various types of couplings have been suggested for both smooth andcorrugated tubing. Couplings used with smooth walled tubing have aparticular problem since there is inherently no convenient means toprovide a mechanical interlock between the fitting and the tubing. Snapon couplings for smooth wall tubing require a recess or extension to bespecially formed in the tubing to provide a complimentary part of theinterlock. This special modification of ordinary smooth walled tubingreduces the thickness and therefore the strength of the tubing at therecess. The increased possibility of failure from the thin section isclearly not desirable.

The modified smooth walled tubing will normally only have a singlerecessat a set distance from the mouth. This structure has the inherentproblem of requiring an exact length of tubing to be inserted into thecoupling. As discussed earlier, specific length requirements result in ahigher frequency of defects and improper connections. An example of acoupling for smooth walled tubing having a recess spaced from the mouthand the above noted disadvantage is illustrated in U.S. Pat. NO.2,452,219 to K. L. Bergvall et al.

Frictional engagements have been used with some success but always havethe potential danger of simply being pulled apart. An example of acoupling for smooth wall tubing is shown in Singers U.S. Pat. No.2,967,067. Singer uses teeth or rib like projections to grasp the smoothwall of a tube. It is inherently based on a frictional engagement whichcan fail.

A coupling for corrugated tubing is shown in the Draudt U.S. Pat. No.3,167,330 which utilizes a relatively complicated mechanism for vacuumcleaner hoses. One section of the Draudt coupling is formed to match thecrest and roots of a specific corrugated tubing. Any change in thecorrugations height or spacing would make a mismatch with the coupling.That is, the coupling is designed for one specific set of measuredcorrugations. The Draudt coupling would simply not be feasibleondrainage tile with various types of corrugatrons.

This invention provides the advantages of an easily assembled couplingwhich securely holds corrugated tubing by means of a mechanicalinterlock. This invention does not require a specific insertion lengthof the tubing into the coupling nor does it require any modification ofthe tubing end. Further, this invention is easily adaptable to otherfittings such as Tees, elbows, etc. without the necessity of employingancillary fastening means. Moreover, the coupling of this invention canaccept corrugated tubing having widely varying corrugation spacing thecorrugation depth. It is only necessary that the effective diameterdefined by the radially inwardly projecting cleats by slightly smallerthan the major outside diameter of the corrugated tube. In this way thedeformable inclined cleats inside the coupling acts as a mechanicalobstruction to the separation of the tubing from the coupling.

The coupling of this invention also has the feature of permitting thetubing to rotate with respect to the fitting. This is advantageous inthat the completed system will be in a stress free condition without anytorque existing. In view of the particular application for which thisfitting is intended, namely drainage systems, it is not necessary thatthe connection be fluid tight. In fact it is advantageous if theconnection is not fluid tight so thatingress of liquid is allowed.

SUMMARY OF THE INVENTION This invention relates to a thermoplasticcoupling for corrugated plastic tubing including an elongated generallycylindrical body have a mouth. The diameter of the cylindrical body andthe diameter of the tubing are elected to permit the corrugated tubingto enter the cylindrical body. A means for permitting the corrugatedtubing to pass into the coupling but impeding its removal includesinclined cleats which are adapted to engage and hold corrugations on thetubing.

FIG. I is a side plan view partially cut away of the coupling of thisinvention.

FIG. 2 is'a section taken through 2-2 of FIG. 1 and is a cross sectionof the coupling with tubing inserted therein.

FIG. 3 is a side view partially cutaway of an alternate embodiment ofthe invention showing a coupling which connects corrugated tubing andsmooth wall tubing, such as a conventional clay tile.

FIG. 4 is a side plan view, partially cut away of an alternateembodiment of the coupling of this invention and includes a corrugatedmid-section.

FIG. 5 is a side plan view partially cut away showing the inventionadapted to a corrugated Tee fitting.

FIG. 6 is a section 6-6 taken through FIG. 5 and indicates a crosssection partially cut away of a Tee coupling embodying the invention.

PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate apreferred embodiment ofthe coupling 8 of this invention which has a generally cylindrical body10 with flared mouths 12 and 14 at either end. An annular indentation 16traverses the circumference of the coupling preferably equidistant fromthe mouths. The flared mouths 12 and 14 are constricted inwardly to forman inside diameter slightly greater than the major outside diameter ofthe corrugated tubing 18. The particular angle of incline of the surfaceof the mouth is not at all critical but it has been found that an angleof -l 5 will allow the corrugated tubing 18 to easily enter the mouth.It is preferred in many cases to employ a flared mouth but this featureis not essential to the invention and couplings as well as fittingswithout a flared mouth serve quite satisfactorily (see FIG. 3).

Protruding radially inwardly from the cylindrical body of the couplingare a plurality of cleats 20. The cleats 20 are generally arranged at acommon vertical plane about the inner periphery or circumference of thecoupling 8. They have inwardly directed generally vertical or steepangle locking faces 22 and outwardly and upwardly directed camming faces24 joined thereto to form a type of ramp. The cleats 20 are axiallypositioned between the mouth and the center of the coupling 8. It isdesirable that the cleats are located in the area of the mouth to enablethem to engage corrugations of the tubing soon after entering thecoupling. In this manner only a minimum of length of tubing needprotrude into the coupling 8 although a greater'length may enter thecoupling by having more than one corrugation pass over the cleats. Ifthe cleats were near the center of coupling the tubing would have toprotrude to nearly the center before it could engage the cleats.

The illustrated tubing 18 has corrugations for purposes of strength,flexibility and generally utility. The corrugated tubing 18 has crests26 connected to roots 28 by means of corrugation walls 30. The walls 30should be nearly vertical or form a large angle with the horizontal inorder to abut against the faces 22 of the cleats 20. Rectangulardrainage openings 31 are arranged circumferentially around the tube inalternate roots to permit ingress and egress of fluids.

There are usually at least three of the cleats 20 around the peripheryof the coupling. Regardless of the number of cleats employed they shouldpreferably be spaced symmetrically about the periphery of the couplingto retain the tubing in a centered position in the fitting. It ispossible, however, to slightly stagger the axial position of the cleats.As illustrated in FIG. 2, the three cleats are equally spaced in a planeat 120 apart. If desired, however, four or.more cleats can be used tosecure the tubing in the coupling. In this case the four cleats shouldbe equally spaced at a common plane 90 apart.

In order to connect the tubing with the coupling the corrugated tubingis simply pressed into the mouth 12 against the camming surfaces 24 ofthe cleats 20. As the tubing progresses into the coupling the cammingsurfaces 24 cause a relative radial movement between the corrugatedtubing 18 and the coupling 10. As the tube enters the fitting there isan expansion of the mouth of the coupling, a slight contraction of thetubing and distortion of the camming face 24 of the cleat.

To permit ease of assemblythe wall thickness of the material forming themouth of the fitting and/or the camming surface 24 may optionally beless than that of the remainder of the fitting to facilitate radialexpansion. It will be recognized that this portion of the fitting whichoverlies the corrugated tubing is not relied upon for any significantload bearing function. The cleats are by design small enough not tocause damage during connection but large enough to engage securely thecorrugations. The particular height of the locking face 22 is notcritical and is dimensioned to be nearly the greatest height allowableand yet permit assembly without difficulty. One satisfactory height forthe cleats has been found to be three-thirty-seconds of an inch for usein connection with tubing having one-fourth of an inch betweencorrugations. The camming slope 24 may also vary somewhat but l0-20, andmore particularly about 15 has been found to work successfully. It ispreferred that the projected length of the camming surfaces 24 do notexceed the distance between the corrugations so that the locking faces22 will fully engage the wall of the corrugation and the mouth of thecoupling will be in a stress free condition. If the projected length ofthe camming does exceed the corrugation spacing the coupling will befunctional but yield less than optimum results. In this connection itshould be recognized that the coupling of this invention is useful withtubing having widely differing corrugation spacing and depth. It will berecognized that the relationship between the angle of the camming faceand the angle of he locking face permits the corrugated tube to enterthe fitting with far less force than is required to remove the tube. Theinner faces 22 of the cleats 20 are ideally nearly vertical but theyneed be at an angle only sufficient to retain the corrugated tubing. Thecleats of FIGS. 1 and 3 are shown as being positioned inwardly from theextremity of the mouth. It will be understood that by positioning thecleats a distance inwardly of the mouth, or extending the mouth beyondthe cleats the tubing will be telescoped further into the fitting. Thisinhibits angulation between the fitting and the tubing and in manyapplications produces a more secure connection. However, the cleats mayoptionally be positioned at the extremity of the mouth so that thecamming surface nearly intersects the end.

Once an individual corrugation has passed inwardly beyond the cleats 20,and into the coupling, it is effectively impeded from moving outwardly.As shown in FIG. 1 an outwardly facing wall 32 of the corrugationengages the inwardly directed faces 22 of the cleat 20. This mechanicalengagement without the benefit of any substantial camming surface willeffectively prohibit the accidental removal of the tubing from thecoupling.

As shown in FIG. 1, two of the corrugations have moved past the cleats20. While it is only necessary that one of the corrugations engages thecleats 20, it is also possible to design the fitting so that three ormore of the corrugations could pass the cleats 20. This flexibility inthe length of tubing that may be received into the coupling reduces thecriticality of the length of tubing in the system. Preferably thedistance between the locking face 22 and the wall of the annularabutment 16 is selected to be approximately a multiple of thecorrugatiori spacing but this feature is not necessarily essential tothe invention.

The coupling is preferably made of a semi-rigid polymeric material suchas polyethylene,

polypropylene, polyvinylchloride, etc. It is clearly necessary that atleast the mouth of the fitting have some resiliency to facilitateassembly.

The annular indentation 16 near the center of the coupling arrests theinward movement of the tubing 18. This indentation acts as a maximumgauging means. Since the principal function of the annular abutment 16,as well as the wall of the first corrugation of the embodimentsdiscussed hereafter, is to arrest inward movement of the tubing it ispreferred that the inner radial exteremity not enter the flow path asdefined by the minor diameter of the corrugated tubing.

An alternate embodiment of this invention in FIG. 3 has a cylindricalbody 34 with cleats 36, which act in cooperation with the corrugations38 as described above. In this embodiment, however, a frusto conicalsurface 40 tapers inwardly to form a substantially cylindrical butslightly tapered body 42. The inwardly tapered section permits itsinsertion into a smooth member 43. The taper of the body is slight and 2has been found generally satisfactory for the purpose of insertion. Thiscoupling is particularly designed to connect corrugated tubing with thesmooth wall pipe such as conventional clay tile.

FIG. 4 illustrates an embodiment of this invention in which the centerportion 44 of a coupling 45 is corrugated. The corrugated section 44 hascrests 46 connected to roots 48 by corrugation walls 50. The cleats 52are again used in conjunction with a tapered mouth 54 to facilitate theinsertion and connection of corrugated tubing into the coupling. In thisembodiment, however, the tapered mouth forms a continuous cammingsurface with an inwardly converging camming surface 56 of the cleat 52.The outer diameter of the tapered mouth is illustrated as being slightlylarger than major diameter of the corrugation on the tubing but thisfeature forms no part of the invention. This particular dimensionalrelationship may arise due to the manufacturing techniques employed. Thecorrugated coupling as shown in FIG. 4 has the particular advantage ofallowing the coupling itself to bend when used to connect tow sectionsof tubing which are not coaxial. Additional strength and tolerance tocompression and tension are also realized by using corrugations in thecenter section of the coupling. These advantages necessarily reduce theprobability of the coupling cracking or breaking. A low failure rate ofthe coupling is particularly important since a broken or collapsedsection must be located underground before it can be repaired orreplaced.

The distance from the mouth 54 of the coupling to its first'corrugationroot normally governs the maximum insertion length of the tubing. Therelative sizes of the coupling and tubing are such that the end of theinserted tubing abuts against the first corrugation wall in thecoupling. Again, the distance between the locking face of the cleat andthe first corrugation is preferably selected to be approximately amultiple of the spacing between corrugations. However, the dimensionscould be varied to permit the tubing to pass within the couplingcorrugations and abut against a central indentation similar to that ofFIG. 1. The maximum insertion depth of the tubing is simply the distancenecessary for the first corrugation to interlock with the cleats 52. Ofcourse, more corrugations may enter the coupling if necessary by passingover the cleats.

A Tee coupling is illustrated in FIGS. 5 and 6. Previously a Tee fittingwithout coupling ends had been used. With this prior art Tee fitting itwas necessary to use a coupling on each of the tree ends of the incominglines and connect them to the Tee fitting. The advantage of the Teecoupling in this situation is obvious. It eliminates the use of threeseparate connectors plus a Tee fitting. The Tee coupling shown in FIGS.5 and 6 has a basic linear section similar to that illustrated in FIG.4. In particular it has a tapered mouth 60 leading into the cammingsurfaces 61 on cleats 62. The cleats 62 engage corrugation walls ofinserted tubing by its inwardly directed face 62. The body of the Teecoupling is formed by corrugations 64 which includes crests 66 connectedto roots 68 by corrugations walls 70.

In the Tee coupling an annular cylindrical shaped conduit branch 72extends outwardly from the side ofv the coupling in fluid communicationtherewith. Conduit branch 72 has cleats 74 with appropriate cammingsurfaces to cooperate with an expanded mouth 76 in the above describedmanner. The corrugated tubing can thus be pushed directly into the threemouths of the Tee coupling by passing over the cleats.

In short, this invention utilizes inwardly protruding cleats and acamming mouth to greatly facilitate the coupling of corrugated tubing.It provides for efficient assembly and security from inadvertent removalof unmodified corrugated tubing from the coupling.

The invention claimed is:

1. In combination, a thermoplastic tubing having corrugations along thelength thereof and a thermoplastic fitting telescopically receivedthereupon with fluid communication therebetween, said corrugated tubingincluding crests and roots connected by walls, said fitting including anelongated generally cylindrical body having at least one generallysmooth-walled mouth, the diameter of the mouth being slightly greaterthan the outside diameter of the tubing to permit the tubing to enterthe mouth and be rotatable with respect thereto;

a plurality of resilient retaining means positioned axially inwardlyfrom the extremity of the mouth and protruding radially inwardly intosaid mouth for retaining the tubing in the fitting, the effectivediameter defined by the retaining means being less than the crestdiameter and greater than the root diameter of the corrugated tubing;

said retaining means comprising a plurality of cleats which include acamming surface disposed at an angle with respect to said walls andconverging inwardly toward said body, the thickness of the materialdefining the camming surface being substantially uniform over the lengththereof,

a locking face integral with said camming surface and extending betweenthe inner extremity of said camming surface and said wall;

said locking face being disposed between adjacent crests of thecorrugated tubing;

said locking face being disposed at a greater angle to the wall than theangle of the camming surface whereby less force is required to insertthe tubing by moving the crest of the corrugated tubing over the cammingsurface and into the mouth than is required to remove the tubing bymoving the crest over the locking face;

abutment means positioned axially inwardly from the locking face adistance at least as great as the distance between corresponding pointson adjacent crests of the corrugated tubing;

said abutment means protruding radially inwardly a distance sufficientto engage a crest of the corrugated tubing to arrest inward axialmovement thereof and terminating at a point which is outside of the flowpath of the corrugated tubing as defined by the roots thereof.

2. The combination of claim 1 wherein the distance between the abutmentmeans and the locking face is substantially a multiple of the spacingbetween the corrugations of the tubing.

3. The fitting of claim 1 wherein the plurality of retaining means areequally spaced circumferentially about the mouth.

4. The fitting of claim 1 wherein the plurality of cleats are generallycoplanar.

5. The coupling of claim 1 wherein the mouth of the coupling is flaredto assist in inserting it over tubing.

6. The coupling of claim 1 wherein the cylindrical body hascorrugations.

7. The coupling of claim 5 wherein a flared mouth at the end of thecoupling tapers into the camming surfaces on the cleats to provide asubstantially continuous tapered surface.

8. The fitting of claim 6 further characterized in that the fitting is aTee having three mouths.

Dedication 3,695,643.-J07m D. Sohmunk, Findlay, Ohio. CORRUGATED TUBECOU- PLING MEANS. Patent dated Oct. 3, 1972. Dedication filed May 23,1974, by the assignee, The H ancoclc Brick Tile Company.

Hereby dedicates to the Public the entire remaining term of said patent.

[Ofiicz'al Gazette August 27, 1974.]

1. In combination, a thermoplastic tubing having corrugations along thelength thereof and a thermoplastic fitting telescopically receivedthereupon with fluid communication therebetween, said corrugated tubingincluding crests and roots connected by walls, said fitting including anelongated generally cylindrical body having at least one generallysmooth-walled mouth, the diameter of the mouth being slightly greaterthan the outside diameter of the tubing to permit the tubing to enterthe mouth and be rotatable with respect thereto; a plurality ofresilient retaining means positioned axially inwardly from the extremityof the mouth and protruding radially inwardly into said mouth forretaining the tubing in the fitting, the effective diameter defined bythe retaining means being less than the crest diameter and greater thanthe root diameter of the corrugated tubing; said retaining meanscomprising a plurality of cleats which include a camming surfacedisposed at an angle with respect to said walls and converging inwardlytoward said body, the thickness of the material defining the cammingsurface being substantially uniform over the length thereof, a lockingface integral with said camming surface and extending between the innerextremity of said camming surface and said wall; said locking face beingdisposed between adjacent crests of the corrugated tubing; said lockingface being disposed at a greater angle to the wall than the angle of thecamming surface whereby less force is required to insert the tubing bymoving the crest of the corrugated tubing over the camming surface andinto the mouth than is required to remove the tubing by moving the crestover the locking face; abutment means positioned axially inwardly fromthe locking face a distance at least as great as the distance betweencorresponding points on adjacent crests of the corrugated tubing; saidabutment means protruding radially inwardly a distance sufficient toengage a crest of the corrugated tubing to arrest inward axial movementthereof and terminating at a point which is outside of the flow path ofthe corrugated tubing as defined by the roots thereof.
 2. Thecombination of claim 1 wherein the distance between the abutment meansand the locking face is substantially a multiple of the spacing betweenthe corrugations of the tubing.
 3. The fitting of claim 1 wherein theplurality of retaining means are equally spaced circumferentially aboutthe mouth.
 4. The fitting of claim 1 wherein the plurality of cleats aregenerally coplanar.
 5. The coupling of claim 1 wherein the mouth of thecoupling is flared to assist in inserting it over tubing.
 6. Thecoupling of claim 1 wherein the cylindrical body has corrugations. 7.The coupling of claim 5 wherein a flared mouth at the end of thecoupling tapers into the camming surfaces on the cleats to provide asubstantially continuous tapered surface.
 8. The fitting of claim 6further characterized in that the fitting is a Tee having three mouths.